Overcenter snap switch



July 17, 1956 R. w. BACHI OVERCENTER SNAP SWITCH 3 Sheets-Sheet 1 FiledAug. 7, 1953 2w m/ 3 u 7 v B 5 0 4 Z 3 3 W x Ill 6 I 2.0 5 5 f a 3 a. g

a 7( ea 5 :ikll v J Bllv l July 17, 1956 R. w. BACHI OVERCENTER SNAPSWITCH 3 Sheets-Sheet 2 Filed Aug. 7, 1953 3440M 1201792"? H Zia/21 July17, 1956 R. w. BACHI 2,755,353

OVERCENTER SNAP SWITCH Filed Aug. '7, 1953 s Sheets-Sheet s s/////7/////A if United States Patent OVERCENTER SNAPSWITCH Robert W.Bachi, Itasca, IlL, assignor to Soreiig Products Corporation, SchillerPark, 111., a corporation of Delaware "Application-August 7, 1953,.Serial No. 372,862

. 11 Claims. -(l. mil-+67) This invention relates to snap switches andhas more particular reference to snap switches of the overcenter ortoggle action type.

Switches of this type generally comprise a flexible contact blade havinga fixed end and a movable end portion cooperable with a stationarycontact, a tripping --arrn-mounted flatwise alongside the contact bladeand capable of fiexure to one side or the other of the plane *of thecontact' blade, and an overcenter compression spring connected betweenthe tripping arm and the blade to effect snap actuation of the movableend portion of the blade in one direction with respect to its stationarycontact in consequence of motion of the arm in the opposite directionpast the plane of the blade.

The snap switch of this invention is disclosed in part,

.butnot claimed, inthe copending application of Robert '-W.- Bachi,SerialNo. 347,437yfiled April 8, 1953.

One of the objects of 'thisin'vention resides in the provision ofa-relatively small overcenter snap switch of the-character describedfeaturing arigid trip -link or -lever having an unusually longstrokeforswitches of this type, and employing a stronger overcenter compressionspring'than was hitherto used to efiect snapping of -the-freeend-portion of the contact blade between the two positions of theswitch.

Theadvantage of providing a relatively strong overcenter spring and arigid trip link'having a relatively long operating stroke is that notonly can'exceptionally good contact pressure he maintained between thecontact bladeand-its cooperating stationary contact even though theswitch mechanism maybe subjected to shocks or vibration; but the initialengagement of the contact ;blade with its cooperating statonary contactduring 'tripping of theswitch will be eifected under exceptionally goodcontact-pressure to-preclude any arcing duringsuch initial engagementofthe'switch contacts.

A further advantage is that ininstances where the free end portion ofthe contact blade operates between spaced stationary contactstobreak onecircuit and make another circuit,-when the switch is tripped, thestationary contactsmay be spaced farther apart than was possibleheretofore in switches of this type, and the spacing of these contactsis far less critical than was the case when the movable;endof'thecontact blade travelled but a short distance from one switchposition-to the other. withthisuarrangement, also, it will beappreciated that vthe increasedinitial contact-pressure as well as finalcontact pressure between the movable end: portion of: the contact blade.and. thestationary contact or. contacts substantially eliminates bouncewhich. hashitherto presented a problern whenever overcenter-snapswitches, of comparable size but of shorter throw were provided.

A related'object resides in the provision of an overcenter snap switchof the character describedwhich will not requireinspection to. make surethat close tolerances .are held'in the manufacture of the operatingparts of the switch,;and which will. operate entirely. satisfactorilywithout such inspections.

I 2,755,353 :litatented July 17; 1:956

Still another object resides in the provision ='of-n'ovel spring seatson the trip link and contactblade which assure unusual stability for therelatively'strong overcen-ter spring by eliminating any tendency for thespring-to "buckle during tripping of the switch.

A- further object of the invention resides in theprovision of a uniquehousing for the snap switch. I

With the above'and' other objects in view,--Whii:h=-Will appear as thedescription proceeds, this inventionaesides inthe novel construction,combinationand'arrangement of parts substantially ashereinafterdescribed,*and*rnore particularly defined by theappendedclaims, it"being understood that such changes in the precise-embodiment:iofi'the herein disclosed invention may be made-as'come *within thescope of the claims.

The accompanying drawings illustratetwo complete examples of thephysical embodiments of 'the invention constructed in accordance with'the bestmodes so 'far devisedfor' the practical applicationofthe-principles thereof, and in which:

"Figure l is a perspective view of the' -housing for'the switch of thisinvention;

"Figure 2 is a longitudinal sectional view through the housing toillustrate its construction and 'showing'the snap switch of thisinvention in place therein;

" Figure 3 is a cross.sectional'viewtaken throu'gHFigure'2'along theplane of'the line'3-"3;

Figure 4 is a separated perspective view of the two housing sectionsshowing "the switchmechanism'mou'nted on'one of the housing sections; V

Figure 5 is a separated'perspective view of'therigid operating'link andthecontactblide of the-switch-of this invention;

Fignre 6 is adiagrammatifideta'il view showing 'the type-ofspring seatswhich are employed to'rnost advantageouslyconnect the overcenter springbetween-the t'rip 'link" andcontact blade;

--Figure 7 is alongitudinal sectional view on"the order of Figure 2'showinga modified embodiment of'the'inventionyand Figure 8 =is'a' crosssectional view through'l igure"7 taken along the plane of the line 88.

Referring-n0w moreparticula'rly to the accompanying' drawings, in' whichlike reference characters indicate like-parts throughout the severalviewsfthe 'numer'al 5 generally designates the housing and 6 theoverce'nter snap-switchpf this invention. The housing comprises upperand'lower' housing sections 7- and '8, respectively, of insulativematerial, and the switch6 is-"mounted upon the lower housing section'8in a'manner -to "be described hereinafter.

'The'lower housing section 3 comprises 'an elongated switch base of=generally rectangular outline, having upright-side'and end edges 9, anda substantially flat un'derside-10. The top of the base has a cavity" 11therein"defininga highlevel support 12 adjacent to one end=of the base,-a low'level supportlli adjacent tothe other end ofrthe base, andrails'or shoulders'15 along'the longitudinal sides of *the'base havingtheir upwardlyfacing surfaces lying in a common plane a slightdistance'above .that of: the high level support-12.

-The upper'housing section 7 'providesa cover which -Medially-of theirends the longitudinal-;sidewalls lof thecover are-provided withrelatively large rectangular notches-2.0 therein, opening to theunderside of the'fcover, and having a depth substantially correspondingto the maximum thickness of the base. These notches are normally closedby mating pads 21 projecting outwardly from the longitudinal edges ofthe base with their outer surfaces flush with those of the cover sides.Elongated shoulders 22 projecting downwardly from the under surface ofthe top wall along the longitudinal sides of the housing and havingtheir surfaces flush with the bottoms of the notches in the cover sidesabut the shoulders 15 on the base to hold the housing sections in properpositions relative to one another with the top of the base spaced fromthe top wall of the housing and the switch 6 accommodated in said space.

Aligning holes 24 and 25 in the cover and base extending verticallythrough the pads 21 and the bottoms of the notches in the cover providefor securement of the housing sections together as by means of therivets 26 or other equivalent fastening means.

The top wall of the housing is provided with a boss 28 projectingupwardly from its center and having a bore 29 which communicates withthe interior of the housing through a counterbore 30. The junctionbetween the bore and counterbore defines an abrupt annular shoulder 31facing the interior of the housing.

The boss slidingly accommodates an actuating member in the form of acontrol button 32. The control button has an enlarged cylindricalintermediate portion 33 slidable in the counterbore 20, a shank 34projecting upwardly in the bore 29 to extend a distance beyond the upperend of the boss, and a reduced stem 35 projecting downwardly from theintermediate portion 33 into the interior of the switch housing toprovide for actuation of the switch mechanism.

As shown in Figure 2, the switch may be provided with two stationarycontacts 36 and 37, the contact 36 being carried by the top wall of thehousing and the contact 37 being carried by the base. It should beunderstood, however. that for many uses, only one stationary contactneed be provided. The contact 37 is mounted on the low level support onthe base, and the contact 36, of course, is mounted directly above thecontact 37, in spaced relation thereto. Each of the stationary contactsis provided by the head of a rivet 38, and these rivets are employed tofix a pair of terminals 39 and 40 to the upper and lower housingsections, respectively, in good electrical contact with the stationarycontacts 36 and 37.

Each of the terminals is bent to substantially right angle shape fromflat strip metal stock to provide an upright leg and a horizontal legintegral with the upright leg. Referring to Figure 3 it will be notedthat the upright leg 41 of the terminal 40 is received in a recess orgroove 42 in one longitudinal edge of the switch base adjacent to thelow level support 13, the groove or recess having a depth substantiallyequal to but not greater than the thickness of the leg 41 so that itsouter surface will lie flatwise against the inner surface of theadjacent cover side wall and substantially flush with the edge of thebase adjacent to the groove. The horizontal leg 43 of the terminal 40projects inwardly over the low level support 13 and seats flatwisethereon, to be held securely on the low level support by the rivet 38which passes through the low level support and provides the stationarycontact 37.

The upright leg 44 of the terminal 39 extends along the oppositelongitudinal edge of the base and may likewise be fiatwise received in ashallow recess or groove therein. In this case, however, the groove 45has been shown provided in the side wall of the cover, and it also has adepth substantially corresponding to but preferably slightly less thanthe thickness of the upright leg 44 of the terminal 39 so that the outersurface of the leg 44 will lie substantially flush with the innersurface of the side wall of the cover and will fiatwise abut theadjacent edge of the base. Again referring to Figure 3 it will be notedthat the upright legs of the terminals 39 4 l and 40 substantiallyembrace the longitudinal edges of the base 8, and this arrangement isdesirable since it pro vides maximum electrical clearance between thedownwardly projecting exposed ends of the terminals. While thedownwardly projecting leg of the terminal for the lower stationarycontact could just as well extend over the end edge of the base, it isdesirable to locate it as shown for the reason that when so disposed thesame switch base and snap switch thereon can be used for switch unitshaving either one or two stationary contacts.

The horizontal leg 46 of the terminal 39 lies flat against the undersideof the top wall 18 of the housing, and is securely fixed thereto by theupper rivet 38 which provides the stationary contact 36.

The switch mechanism 6 comprises a flat elongated contact blade 48, ofresilient spring stock having one end fiatwise secured on the highsupport 12 by a rivet 49 passing therethrough, and having its free endportion extending between the stationary contacts 36 and 37 forcooperation with one of them in either position of the switch. As shownbest in Figure 5 the contact blade 48 has an elongated central cutout 50therein, one edge 51 of which lies closely adjacent to the high levelsupport and faces the free end of the blade. The other edge 52 of thecutout is at the free end portion of the blade and faces the fixed endthereof. A tongue 53 on the mid portion of the edge 52 and projectinginwardly there from toward the edge 51 provides one of the seats for theovercenter spring, and it will be noted that the opposite edges 54 ofthe tongue converge toward its extremity.

The outer end of the spring blade is capable of fiatwise ficxuredownwardly into engagement with the stationary contact 37 (as seen inFigure 2) or upwardly away from the stationary contact 37 and intoengagement with the stationary contact 36. Preferably a contact rivet 55having heads exposed at both faces of the contact blade is fixed to itsouter end portion for cooperation with the stationary contacts.

The opening 50 in the contact blade accommodates a trip link 57 whichaccording to this invention comprises a rigid lever stamped from sheetmetal stock. The inner end portion 58 of the lever is received in theopening 50 of the contact blade and is provided with a crease 59 intowhich the bearing edge 51 on the fixed end of the blade projects tofulcrum the lever for back and forth swinging motion through the openingin a path substantially normal to the plane of the blade andintersecting said plane. The outer end portion 60 of the lever comprisesa substantially flat arm radial to the hinge or fulcrum axis of thelever, and is joined to the curved inner end portion 58 by means of asubstantially flat inner arm 61 on the lever disposed at a relativelylarge obtuse angle with respect to its outer arm 60.

The rigid lever or trip link 57 has a lengthsubstantially shorter thanthat of the contact blade, and in fact shorter than the longitudinaldimension of the opening 50 in the blade, so that when it is seated onthe knifeedged bearing 51 at the fixed end of the blade the extremity ofthe lever will travel in an are which is spaced a distance from thespring seat defined by the edge 52 of the opening and the tongue 53which projects therefrom. The outer end of the lever is also providedwith a square-cut shoulder 62 and a tongue 63 projecting outwardlytherefrom and having converging sides 64 similar to those on the tongue53 of the contact blade. The shoulder 62 and the tongue 63 also define aspring seat on the lever which is cooperable with the spring seat on thecontact blade to retain the overcenter compression spring 66 connectedbetween the outer end of the lever and the outer end portion of thecontact blade.

The compression spring 66 may be an ordinary helically wound spring, butit has been found preferable to employ a barrel-shaped spring as shownbest in Figure 2.

As thereinseen, the intermediate. convolutions of the .spring havesubstantially, greater diameter than those at the opposite ends .of thespring, and it is important to note that the end convolutions 67 aregroundto provide .end surfaces on the spring which lie in planes normalto the axis of the spring. Moreover, these end convolutions have. adiameter such that they will snugly embrace the tapered sides of thetongues 53 and 63 near their bases ...as seen in Figure6.

These wedge-like connections between the ends of the spring. and thetapered tongues 53 and 63 provide exceptionally good rocking seats forthe overcenter spring .and unusual stability to prevent buckling of thespring as might be the case if the tapered tongues were to fit .,looselyin the end convolutions of the spring.

.The barrel spring 66, of course, -will always be under substantialcompression when confined between the spring .-seats on the trip linkand contact blade, and this assures thatineither the upwardly ordownwardly flexed condi- ...tion..of..the contact blade its contact willbe held in engagement-with one or the other of the stationary con-.tacts withexceptionally good contact pressure therebetween.

I It willbe noted that with the barrel spring 66 properly connectedbetween the outer end portions of the trip link and contact blade, thelatter is placed in tension by .the spring while, the trip link isplaced in compression. .lnother words, the barrel spring exerts a forceupon the trip link tending to move the same endwise toward the fixed.end of the contact blade to thus assure that the .creased inner end ofthe trip link will remain properly seated or fulcrumed upon the bearingedge 51.

.Attention is also directed to the fact that the inner end, portion. 58of the trip link has a width greater than .tjhatof. the opening 50 inthe contact blade, and is pro- ,vided with relatively. narrow notches 69in its opposite .side edges in line with the crease 59 vto receive theedge ,portionsof the contact blade which define the longitudinal Iedges.,of the opening-50 therein. The purpose of this inte rlocking connectionbetween the inner end portion of the trip link and the fixed end portionof the contact blade is to assure that the link willremain properlyseated upon the bearing edge 51 during switch assemblyoperationsorduring. the applicationof any abnormal high im- {pact forcesonto the link which would tend to unseat the .same.

,The fswitch. illustrated in Figure 2 is-further provided with acompression spring 71.having one end portion .received in an upwardlyopening well 72 in the base i; of the housipgand its upper end bearingagainst the underside of. the arm 60. of the trip link closely adjacentto. the junction of its inner and outer armsto bias the trip linkupwardly toward, the top wall of the housing. In order to assure againstdisengagement of the biasing spting71 from the underside of the lever atongue 73 is struck downwardly from the arm 66 to engage in theconvolutions at the upper end of the spring and thereby prevent shiftingof the spring with respect .to the lever.

As seen in Figure 2 the biasing spring 7l'holds the trip link or lever57 swung upwardly in one of the two positions of the snap switchmechanism, which position is defined by the. engagement of the outer arm64) of the linkwith the adjacent. end of the stem 35 on the actuat- ,ingbutton 32. In this position of the parts the actuatingbutton32 is heldby the spring '71 at. its upward limit .oftraveldefined by theengagement of the enlarged medial portion 33 on. the button withthe.downwardly facing j'shoulder 31 at the bottom of the counterbore intheboss28 in which the actuating button is slidably mounted.

Attention isdirected to the fact that in the position of theswitchillustrated.in Figure 2 the outer arm 6% of ,the triplink or lever. is.held spaced a substantial distancfrom. the plane. of the contactbladetd-by the combined forces of the spring 71 and the barrel spring66. The

' hitherto possible.

overcenter spring 66 also exerts a substantial downward .force on thecontact blade to hold the same flexed away from the arm 69 of the triplink and maintain the movable. contact 55 on the blade engaged with thestationary contact 37 with exceptionally good contact pressuretherebetween.

It will also be noted that the lever must be. swung downwardly on itsfulcrum through an arc of substantial length, by inward depression ofthe actuating button, before the arm60 of the trip link will reach aposition coinciding with the plane of the contact blade and whichposition represents dead center ofthe toggle-connected link and. blade.Downwardswinging of the, trip link beyond the dead-center position, ofcourse, effects tripping of the switch by the overcenter barrel spring66Yto snap the contact end of the blade upwardly into engagement withthe upper stationary contact 36 of theswitch.

This second position of the switchparts is indicated in constructionlines in Figure 2, and willobtain as long as the actuating button 32 isheld depressed. Upon release of the actuating button the biasing spring71 returns the switch to the position shown inv full lines in Figure 2,and it will be thus appreciated that the biasing spring '71 has a forcegreat enough to overcome that of the overcenter barrel spring 66. Thetrip link or lever 57, of course, will remain properly seated on itsbearing edge or fulcrum 51 despite the application of downward forcethereto by the actuating button, and despite the force exerted thereonbythe biasing spring. This results from the fact that for all normaloperation of the switch, the crease S9 ,in the link is deep enough toprevent unseating of the link.

As stated previously, the limit of upward swinging motion of the triplink or lever 57 is defined by. theengagement of the outer arm 60 withthe stern of the actuating button. Downward swinging motion of thetriplink may be. limited to the stroke of the actuating button '32. or,in other words, the distance the shank portion of the buttonnormallyprojects from the top ofthe boss' 28 on the top of the switch housing.Alternatively. the downward limit of swinging motion of the lever canbedefined by the engagement of its outer arm 69 with a ledge 75 in therecess- 11 in the top of the switch base, directly beneath the actuatingbutton.

- It will be seen that in swinging between its upper and lower limits,the-arm 6t? on the trip link or lever travels through an arc ofrelatively great length for small snap switches of thisv type, and thisis one of the features of the switch of this invention. Since the lever.must swing relatively far before it reaches thedead-center positioncoinciding with the plane of the contact .blade, the stationary contactsmay be located fartherapart than was in addition the overcenter barrelspring 66 can be relatively strong to effect engagement, both initialand final, between the movable contact and either stationary contactunder greater pressure than has been possible in the past insmallovercenter snap switches of the type herein concerned.

This is an exceptionally valuable feature wherever the snap switch is.to be used in environments where it might be subjected to vibration orshocks, in that it eliminates substantially. all tendency of thecontacts to bounce or to are either during their initial engagement orafter their engagement under the full force of the overcenter spring.This assures long life of the contacts and of the spring mechanismgenerally in such installations as that shown and described in thecopending application of Robert W. Bachi, Serial No. 347,437 filed'April 8, 1953, wherein the switch forms part of a powerfulelectromagnetically operated latch mechanism of the type used onrefrigerator doors.

The third terminal 77 of the switch is similar to the terminals 39 and4d and has one leg 78 thereof flatwise overlying the high level support12 in superimposed relation with the fixed end of thecontactblade,-and-is secured to the base by the same rivet used toanchor the contact blade to the switch base. Its downwardly projectingleg 79 is received in a shallow groove or notch 80 in the adjacent endedge of the base so that the outer surface of the leg 79 will liesubstantially fiush with or leven project slightly from the adjacent endedge of the ase.

Accordingly, the outer surfaces of all of the downwardly depending legsof the terminals 39, 40 and 77 are disposed in the telescoping jointbetween the cover and the base and do not interfere with sliding of thecover over the base at the time the two housing sections are securedtogether. Moreover, since the depending legs of the terminals are heldsnugly engaged in shallow grooves in the housing by the telescopingengagement of the housing sections, any lateral forces exerted upon theterminals tending to bend the same will not be transmitted to theriveted connections between their inner ends and the switch base; andthese rivets will remain tight at all times.

In the assembly of the switch device all of the switch parts areassembled on the base 8 of the switch housing. The trip link or lever 57may then be held swung downwardly part way toward or near dead centerposition (not shown) by a tool projected laterally across the top of thebase over one of the two pads 21 which project from its longitudinalsides. This is done to maintain the barrel-shaped overcenter compressionspring 66 properly connected between the trip link or lever and thecontact blade until such time as the cover is in position on the basecompleting the housing. While the trip link or lever is held thusdepressed, the cover is slipped downwardly over the base while theactuating button 32 is held depressed, and with one of the notches 20 inthe opposite longitudinal sides of the cover accommodating the tool bywhich the trip link or lever is held depressed. Before the cover reachesits final position fully enclos ing the base, the stem 35 on theactuating button will engage the outer arm 60 of the trip link or leverand the tool may be withdrawn from either notch in the cover, and thecover thereafter pushed down to its final position and riveted orotherwise secured to the base in the manner described.

It will be seen, therefore, that the interlocking connection between thecover and the base afforded by the notches 20 in the cover sides and thepads 21 on the sides of the base not only provides stability for thetelescoped joint between the cover and the base, but these notches alsoprovide access ports to enable the overcenter spring 66 to be heldproperly connected between the lever and contact blade by a toolaccommodated in one of these notches during the application of the coverto the switch base.

While the switch shown and described thus far is of the type which isbiased to return to one of its two positions following tripping thereofby means of the actuating button, the switch shown in Figures 7 and 8 isof the type wherein the contact blade will remain in either one of itstwo positions until it is actuated in the opposite direction. In otherwords, there is no biasing spring for returning the trip link or leverto the same position following actuation of the switch.

The construction of the switch mechanism in this case may be exactly thesame as previously described, but an actuating lever 82 is providedinstead of the actuating button to swing the trip link or lever 57 fromone position to the other. The actuating lever is pivotally munted onthe exterior of one longitudinal side of the switch housing, as by apivot pin 83, to swing about an axis extending lengthwise of the contactblade of the switch and closely adjacent to the plane thereof. The levermay conveniently comprise a relatively flat thin piece of insulativematerial pivotally supported on the pin 83 and having a handle 84projecting outwardly therefrom to provide for swinging of the lever.

The lever has a jaw portion 85 formed thereon projecting through a slot86 in the adjacent longitudinal side of the switch housing, with theopposite fingers 87 of the jaw reaching around the adjacent longitudinaledge of the contact blade and loosely embracing the outer arm 60 of thetrip link or lever 57 near its extremity.

In this case the two switch positions of the trip link or lever aredefined by the actuating lever 82 which has inwardly facing shoulders 88on its upper and lower side edges alternatively cooperable with a stopplate 89 on the adjacent side of the switch housing to limit the extentof rocking motion of the actuating lever. Thus, as illustrated in Figure7, the barrel-shaped overcenter spring 66 is shown reacting upwardlyagainst the outer arm 6%) of the trip link and through said arm againstthe upper finger 87 on the actuating lever to hold the same in itsclockwise limit of rocking motion seen in Figure 8, defined by theengagement of its lower shoulder 88 with the stop plate 89. When theactuating lever 82 is swung in a counterclockwise direction as seen inFig ure 8 the upper finger 87 on the actuating lever moves the trip linkdownwardly on its fulcrum past dead center and the switch snaps to itssecond position at which the barrel spring 66 reacting through the outerarm 60 of the trip link and the lower finger 87 on the actuating leverholds its upper shoulder 88 engaged with the stop plate 89.

With the exception of its housing and terminals, the switch shown inFigures 7 and 8 has all of the features of the switch shown in Figure 2.

From the foregoing description taken together with the accompanyingdrawings it will be readily apparent to those skilled in the art thatthis invention provides an improved overeenter snap switch featuringexceptionally good contact pressure even upon initial engagement of thecontacts during tripping of the switch, and wherein no close inspectionfor tolerances of the switch parts is required; and that the arrangementof terminals and the housing construction generally greatly facilitatesthe znsembly of the housing sections and enables the parts of the switchmechanism to be properly engaged during such assembly of the switchmechanism.

What I claim as my invention is:

1. In an overcenter snap switch of the type including can elongatedflatwise flexible contact blade having a fixed end portion and a freeend portion movable toward and from engagement with a stationarycontact, a housing for the switch comprising: an elongated base ofinsulative material having upright edges and having a recess in its topdefining a low level support adjacent to one end of the base and a highlevel support adjacent to the opposite end of the base; a pair ofterminals for the switch, each bent to substantially right angle shapefrom flat strip metal stock and each having one leg thereof fiatwisesupported on one of said supports on the base and its other legprojecting downwardly through a notch in an adjacent edge of the base tothe exterior of the housing so that the outer faces of said downwardlyprojecting legs of the terminals lie substantially fiush with thesurfaces of said edges adjacent to the notches therein; rivets passingthrough said supports and the legs of the terminals thereon to fix saidterminals to the base, the rivet through the low level support having ahead providing a stationary contact exposed at the top of the base; thefixed end portion of the contact blade of the switch being securedfiatwise on said high level support in electrical contact with the legof the terminal thereon by the other of said rivets, and the free endportion of the contact blade overlying and being cooperable with saidstationary contact; and a cover for the housing secured over the base toenclose the switch mechanism thereon, said cover having a wall overlyingthe top of the base in spaced relation thereto, and having side wallsclosely telescoped over the upright edges of the base and the outersurfaces of the downwardly projecting legs of the terminals thereon.

i9 2. In an overcenter snap switch of .thetypeincluding an, elongatedflexible contact bladehaving a'fixed end portion and a free endportioximovable toward andfrom engagement with a stationarycontact,.a.housing=for the switch comprising: cooperating upper. andlower elongated housing sections, theupper housing section providing acover open at its bottom and having a top v.wall and downwardlyprojecting side walls, and the lower housing section 'cornprising aswitch base telescoped into the open bottom of the coverv and havingupright edges relatively closely slidingly engaged withthe innersurfaces ofthe cover side walls; means securingsaidhousingsectionstogether .with the top of the base spaced from the top .wall of thehousing; the baserhaving a recess in its-top defining a low levelsupport adjacent to one end-of the housing and a high level supportadjacent to the opposite end of the housing; a pair of terminals for theswitch, each bent substantially to right angle shape fromfiat stripmetal stock and each having one leg thereof ,flatWisereceived in arelatively shallow upright groove in one of said housing sections at thetelescoping joint therebetween and projecting to'the exterior of 'thehousing from the'underside thereof, and having its other leg flatwiseseated on one of said supports on the bas and riyets passing throughsaidsupports and said other legs of the terminals thereon to fix saidterminalsto:the--base,zthe rivet through the low level support having ahead providing a. stationary contact exposed 'atthetop of'the base; thefixed end portion of the contact bladeof the switch being securedflatwise onsaidhigh-level support in electrical contact with the leg ofthe terminal thereon by the other of said rivets,- andthe free-endportionof' the blade being cooperable with said stationary contact.

3. The overcenter snap switch set forth in claim 2 further characterizedby the provision of a second stationary contact fixed to the top wall ofthe housing directly over but in spaced relation to the first designatedstationary contact and likewise cooperable with the free end portion ofthe contact blade, and a third terminal bent to substantially rightangle shape from flat strip metal stock and having one leg secured tothe top wall of the housing in electrical engagement with said secondstationary contact and having its other leg extending downwardly througha relatively shallow groove in one of the housing sections at thetelescoping joint therebetween to the exterior of the housing at itsbottom.

4. The overcenter snap switch set forth in claim 3 wherein said secondstationary contact comprises the head of a rivet by which the thirdterminal is secured to the top wall of the housing.

5. A switch device of the character described, comprising: an elongatedhousing of insulative material including a cover section open at itsbottom and comprising a top wall and downwardly extending side walls,and a bottom section telescoped into the open bottom of the coversection to close the same, said bottom section comprising a switch basehaving a recess in its top defining a high level support adjacent to oneend of the housing and a low level support adjacent to the other end ofthe housing; cooperating shoulders on the base and the cover sectionengaging one another to hold the top of the base in spaced relation tothe top wall of the housing, said base having a pad projecting from onelongitudinal edge, and the corresponding longitudinally side of thecover having a notch therein opening to the bottom of the cover toaccommodate said pad on the base during telescoping of the cover ontothe base and which notch is closed by said pad when the cover isproperly positioned on the base with said shoulders on the housingsections in engagement with one another; means securing said housingsections together with said shoulders thereon in abutting engagementwith one another; an overcenter snap switch mounted on the top of saidbase in the space between it and the top wall of the housing, said snapswitch including a flatwise flexible contact blade having one end,seate'dflatwise on and tfixedto said highlevel support anditsrother endportion overlying the low. level support,

.rnounted onthe cover section of-the housing witha por- ,tionnormallybearingagainst thetriplinkto limit swingingmotion. thereof inone direction under theinfluence of said overcenter spring-so as tothereby preventdetachment of the spring fromthe trip link, said actuatorhaving a portion extending through the cover .section of the housing andaccessible at the exterior thereof; and-said notch in the side ofthecover. accommodating a tool-by which the trip linkmay be held connectedwith the overcenter spring during'telescoping of the cover section ontothe switch base to. a position atiwhich, said portion of the actuator isbrought to bear upon the trip link.

-6.v In anovercenter snap switch: an elongated contact blademounted atone .end for. substantially fiatwisernotion of itsopposite end. portionalong a defined path into .and .out of engagement with a stationarycontact, said blade having an elongated opening intermediate its ends; alever fulcrumedvat one end. adjacentto the mounted end of said contactblade andextending in substantially the same direction as the blade,said lever beingshorter than.-the contact blade and its outerend portionbeing movable along said path of travelof: the contact blade back. andforth through said .opening-inthe blade; an overcenter expansion springconfinedunder compression betweenvspaced outer end portions of thecontact blade and said lever to yieldingly urge the blade in onedirection and the lever in the opposite direction; and opposing spacedapart spring seats on the outer end portions of the blade and lever toreceive the ends of the spring and hold the same operatively connectedwith the blade and lever, each of said spring seats comprising a tongueprojecting into an aperture in the adjacent end of the spring and havingopposite tapering side surfaces both of which are at ali times engagedby the adjacent end of the spring, said surfaces on the tongue divergingto a dimension larger than that of said aperture into which the tongueprojects so that engagement of the spring ends with the blade and leveris limited to contact thereof with the tapering side surfaces of each ofsaid tongues.

7. The overcenter snap switch set forth in claim 6 wherein saidovercenter spring is a helically coiled expansion spring having annularend convolutions which provide said apertures into which the taperedtongues project to minimize the danger of the spring buckling duringoperation of the switch.

8. In an overcenter snap switch: an elongated substantially flat contactblade mounted at one end upon a support, and being fiatwise flexible toenable its outer end portion to be moved into and out of engagement witha stationary contact, said blade having an elongated openingintermediate its ends defining a bearing edge adjacent to but facingaway from the mounted end of the blade and a spring seat adjacent to theouter end of the blade facing said bearing edge; a lever fulcrumed atone end upon said bearing edge for back and forth rocking motion throughsaid opening in the blade so as to enable the outer end portion of thelever to be moved between alternate positions spaced to one side or theother of the plane of the blade, said lever being shorter than the bladeand having a spring seat on its outer end in spaced opposingrelationship to said spring seat on the blade, the fulcrumed end of thelever being wider than the opening in the contact blade and havingnotches in its opposite side edges into which edge portions of the bladealong the longitudinal dimension of said opening project to provide aninterlocking connection between the lever and blade to preventaccidental displacement of the lever from its fulcrum; and overcenterexpansion spring confined under compression between said spring seats onthe lever 11 and blade to yieldingly hold the blade flexed in onedirection and the lever swung in the opposite direction; and means formoving the lever from one toward the other of said alternate positionsthereof.

9. The overcenter snap switch set forth in claim 8, wherein said leveris stamped from a flat piece of sheet metal and said fulcrumed endthereof is rigid and has a crease therein into which the bearing edge onthe blade projects to fulcrum the lever from the mounted end portion ofthe blade, said lever having a substantially flat outer portion which issubstantially parallel and radial to the axis about which the leverswings, and said notches in the fulcrumed end of the lever extendinginto the opposite side edges of the creased end portion of the lever inline with the crease therein.

10. In an overcenter snap switch: an elongated con tact blade mounted atits rear end for flatwise up and down motion of its front end portioninto and out of engagement with a stationary contact, said blade havingan elongated opening in an intermediate portion thereof, the reartransverse edge of said opening providing a bearing facing toward thefront end of the blade; means on the forward transverse edge of saidopening defining a spring seat; a rigid lever formed as a stampingseparate from the contact blade and having a short arm adjacent to themounted end portion of the contact blade and projecting downwardlythrough the opening in the contact blade from one side thereof, saidshort arm having a transverse crease therein in which said bearing edgeof the contact blade projects to fulcrum the lever for pivotal motionabout a transverse axis parallel to the plane of the contact blade,

said lever having a long arm projecting forwardly from said short armtoward the forward transverse edge of the opening in the contact bladebut terminating short of the spring seat thereon, and said long arm ofthe lever being movable up and down through the opening in the contactblade during swinging motion of the lever about its pivot axis toalternate positions at which the outer end portion of said long arm ofthe lever is disposed at one side or the other of the contact blade;means on the outer end of said long arm of the lever defining a springscat opposing that on the contact blade; an overcenter spring connectedbetween and confined under compression by said spring seats on the leverand the contact blade, for yieldingly urging the contact blade in onedirection and the long lever arm in the opposite direction; and meansfor swinging the lever from one toward the other of said alternatepositions of the long arm thereof.

11. The overcenter snap switch set forth in claim 10 furthercharacterized by the fact that said long arm of the lever has an outerend portion offset downwardly and lying substantially in a radial planecontaining the pivot axis of the lever.

References Cited in the file of this patent UNITED STATES PATENTS2,556,216 Raney June 12, 1951 2,657,288 Hubbell Oct. 27, 1953 FOREIGNPATENTS 551,021 Great Britain Feb. 4, 1943

